Engine control device of contruction machinery

ABSTRACT

An engine control device for a construction machine of the present invention is configured so that the engine control device comprises an engine as a power source, a controller for performing an automatic stop control to automatically stop the engine when a predetermined automatic stop condition is met, a water temperature sensor for detecting a cooling water temperature of the engine, and that after start-up of the engine, even if the automatic stop condition is met, the engine is not automatically stopped until the detected water temperature reaches a predetermined value or more to complete a warm-up operation. The engine control device is also configured so that before the engine is automatically stopped, a cool-down operation of the engine is performed as required and after the engine is stopped, the engine is restarted as required and the warm-up operation is performed.

TECHNICAL FIELD

The present invention relates to an engine control device for aconstruction machine in which an engine is automatically stopped (autostop) in non-operation time.

BACKGROUND ART

A construction machine including an automatic stop function forautomatically stopping an engine when predetermined automatic stopconditions (for example, a gate lever for opening and closing a gatewayto a cabin is opened and a lever for operating a work actuator is innon-operation) is met has been disclosed in Japanese Patent Laid-OpenNos. 2000-96627 and 2001-41069.

However, when the automatic stop conditions are met, an engine isautomatically stopped only by the condition. Thus, when for example anoperator leaves a machine for inspections or the like during a warm-upoperation after start-up of the engine particularly in the cold time,the engine is automatically stopped in the middle of the warm-upoperation.

As a result, the engine is automatically stopped while keeping alow-temperature state in a non warm-up machine, and after that, arestarting operation of the engine puts a heavy load on the engine andperipheral devices such as a water pump and a cell motor (hereinafterreferred to as engine and the like), which is likely to cause a failure.

Further, since the restarting operation of the engine must be performed,a heavy load is put on an operator's operation.

It is noted that although only canceling an automatic stop controlbefore warming up the machine is enough to avoid this situation, theoperation is troublesome or can be forgotten.

Further, other problems are as follows:

-   1) since the engine can be suddenly stopped while being in a high    temperature state, a heavy load is put on the engine and the like    from this point of view;-   2) when a period after the engine is stopped by the automatic stop    control until restarting the engine is long particularly in the cold    time, the engine is cooled down and the restart becomes troublesome.    Thus a heavy load is put on the engine and the like even in this    case.

It is an object of the present invention to provide an engine controldevice for a construction machine provided with an automatic stopfunction, which can protect an engine and the like.

DISCLOSURE OF THE INVENTION

To solve the above-mentioned problems the present invention adopted thefollowing configurations.

The present invention is configured so that an engine control device fora construction machine comprises an engine as a power source, controlmeans for performing an automatic stop control to automatically stop theengine when a predetermined automatic stop condition is met, and warm-upstate detecting means for detecting a warm-up state of the engine andthat the control means is adapted to perform the automatic stop controlin a condition that completion of a warm-up operation for the engine isdetected by the warm-up state detecting means.

According to the configuration of the present invention, since theautomatic stop control always serves after the warm-up operation of theengine is completed, there is no fear that the engine is automaticallystopped keeping a low temperature state before warming up. As a matterof course, the engine is not restarted under a non warm-up state.Therefore, a load on the engine and the peripheral devices can bereduced.

Further, there are no troubles of canceling the automatic stop controlbefore warming up and of restarting the engine for warming up.

Further, the present invention is configured so that an engine controldevice for a construction machine comprises an engine as a power source,control means for performing an automatic stop control to automaticallystop the engine when a predetermined automatic stop condition is met,and cool-down necessity detecting means for detecting whether or not theengine is in a state where a cool-down operation is required and thatthe control means performs the automatic stop control in a conditionthat a cool-down period is kept before the engine is automaticallystopped when the cool-down necessity detecting means detects that theengine is in an operation state where it requires the cool-downoperation.

According to the configuration of the present invention, since thecool-down operation of the engine is performed as required before theengine is automatically stopped, there is no fear that the engine isstopped keeping a high temperature state. Accordingly, generation oftroubles such as seizing of a turbine shaft is prevented so that theengine and the like can be protected.

Further, the present invention is configured so that an engine controldevice for a construction machine comprises an engine as a power source,control means for performing an automatic stop control to automaticallystop the engine when a predetermined automatic stop condition is met,and warm-up necessity detecting means for detecting whether or not theengine is in a state where it requires a warm-up operation of theengine, and that the control means is adapted to automatically restartthe engine when the warm-up necessity determining means detects that theengine is in a state where the warm-up operation is required after theengine is automatically stopped by the automatic stop control.

According to the configuration of the present invention, since after theengine is stopped by the automatic stop control in the cold time theengine is automatically restarted as required and the warm-up operationis performed, the engine can be maintained at a temperature statesuitable for the next start.

Thus, a load on the engine and the like due to the restart of the engineat a low temperature can be eliminated and the restart of the enginebecomes easy.

Furthermore, since the automatic stop control is utilized, an essentialobject of the control of fuel saving and the like can also be attained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a first embodiment of the presentinvention;

FIG. 2 is a flow chart for explaining an action of the first embodiment;

FIG. 3 is a block diagram showing a second embodiment of the presentinvention;

FIG. 4 is a flow chart for explaining an action of the secondembodiment;

FIG. 5 is a flow chart for explaining an action of a third embodiment ofthe present invention;

FIG. 6 is a block diagram showing a fourth embodiment of the presentinvention; and

FIG. 7 is a flow chart for explaining an action of the fourthembodiment.

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment (see FIGS. 1and 2)

An engine 1 as a power source is controlled by a controller 2 as controlmeans.

The controller 2 includes an engine controller 3 for sending a signal ofa stop command to the engine 1 (particularly engine governor controller)and an automatic stop necessity determining unit 4 for determiningwhether or not it is necessary to perform an automatic stop control as aprevious stage.

To this automatic stop necessity determining unit 4 is input a signalrelating to a predetermined automatic stop condition. Necessity of theautomatic stop control is determined based on this automatic stopcondition signal.

It is noted that the automatic stop condition is, for example, any oneor both of the following conditions:

-   1) a gate lever for opening and closing a gateway of a cabin is    opened;-   2) an operating lever as operation means for operating a work    actuator is in non-operation.

The automatic stop condition is detected by a switch for turning ON/OFFin synchronization with movements of the respective levers and sent tothe automatic stop necessity determining unit 4.

In a case where a machine of a canopy structure having no cabin hasalternative means for the gate lever with regard to the above 1), thefact that this alternative means is operated becomes a condition of 1).For example, when an operating lever box provided with an operatinglever is liftable and lowerable and is lowered at the seating of anoperator, a condition of 1) is that the operating lever box is lifted(opened).

Further, a water temperature sensor 5 as a temperature detector fordetecting a cooling water temperature of the engine, as an enginecoolant is provided. In a condition that a water temperature A detectedby the water temperature sensor 5 is a predetermined temperature(hereinafter referred to as warm-up completion temperature) As or more,the automatic stop control becomes possible. In other words, even thoughthe automatic stop conditions are met, if a requirement of A≧As is notsatisfied, the automatic stop control is not started.

Actions of these points will be explained by way of a flow chart of FIG.2.

As soon as the automatic stop control is started, it is determinedwhether or not the automatic stop conditions are met (Step S1). In acase of NO, the processing flow does not advance to the next step. In acase of YES, it is determined whether or not the requirement of A≧As issatisfied in Step S2.

Here in only a case of YES (in a case where the detected watertemperature A is the warm-up completion temperature As or more), theengine 1 is automatically stopped in Step S3.

As described above, after the warm-up operation of the engine theautomatic stop control always serves. Thus, even if the operator leavesa machine for inspections or the like after starting the engine and theautomatic stop conditions 1) and 2) are met, the engine 1 is not stoppedif it is prior to warming up (in a case of A<As).

Accordingly, there is no fear that the engine 1 is stopped while keepinga low temperature state in a non warm-up machine and a restartingoperation puts a load on the engine and the peripheral devices.

Further, in a machine having a function of canceling the automatic stopcontrol, there are no troubles of previously canceling the automaticstop control before warming up as well as restarting the engine forwarming up.

Second Embodiment (see FIGS. 3 and 4)

Only different points from the first embodiment will be described in thefollowing embodiments.

When the engine 1 is stopped while keeping a high temperature state,troubles such as seizing of a turbine shaft can be generated.

Thus, in the second embodiment, a cool-down operation of reducing(cooling) a temperature of the engine 1 is automatically performed asrequired before the automatic stop control is started. In this case, aperiod of the cool-down operation is automatically selected among twotypes in accordance with a detected temperature and is counted by atimer 6 provided in the engine controller 3.

Namely, in a flow chart of FIG. 4, when the automatic stop conditionsare met (in a case of YES in Step S11), the detected water temperature Ais compared with a predetermined reference temperature A1 in Step S12.If a requirement of A≧A1 is satisfied in Step S12, a set value B1 as acool-down time B is selected in Step S13. If a requirement of A<A1 issatisfied, a set value B2 as a cool-down period B is selected in StepS14. Here B1>B2 is satisfied.

In the subsequent Step S15, a timer count is performed at the set valueB1 or B2, and after a count up (in a case where the number of counts T>Bis satisfied so as to exceed the set value; in a case of YES in StepS16) the engine 1 is automatically stopped in Step S17.

It is noted that a fixed cool-down period can be appropriatelydetermined with regard to the set values B1, B2 of cool-down periods inaccordance with a cool-down performance, a use environment or the like.In this case, if the reference temperature A1 is set to a minimum valueof a temperature at which a cool-down is required, since the cool-downoperation is not required at A<A1, the set value B2 on the short timeside is 0 (no cool-down operation).

Further, three or more set values of the cool-down periods may beautomatically selected.

Thus, since the cool-down operation of the engine 1 is performed asrequired before the engine is automatically stopped, there is no fearthat the engine 1 is stopped keeping a high temperature state.Accordingly, generation of troubles such as seizing of a turbine shaftis prevented so that the engine and the like can be protected.

Further, in the second embodiment, since the cool-down period B isautomatically selected from two periods B 1 and B2 in accordance with alevel of the detected water temperature A, a right appropriate cool-downoperation can be performed.

Third Embodiment (see FIG. 5)

The third embodiment is configured as a modified embodiment from thesecond embodiment so that an engine is stopped after it is determinedwhether a cool-down operation is required or not and completion of thecool-down is detected.

Since the block configuration of the third embodiment is apparently thesame as FIG. 1, a drawing is omitted while using FIG. 1.

Actions of the third embodiment will be described with reference to FIG.5. After it is determined that the automatic stop conditions are met inStep S21, the detected water temperature A is compared with a cool-downstarting temperature As1 predetermined as a temperature at which thecool-down operation should be started (Step S22).

In a case of NO, that is in a case of A<As1, since the cool-downoperation is not required, an engine stop action is immediatelyperformed in Step S23.

On the other hand, in a case where it is determined to be A≧As1 in StepS22 (in a case of YES in Step S22), after the cool-down operation isperformed until the detected water temperature A is reduced to acool-down completion temperature As2 or less predetermined as atemperature at which the cool-down may be completed (in a case of YES inStep S24), the engine is stopped in Step S23.

As described above, since the cool-down is performed only as requiredand the automatic stop control serves to stop the engine 1 when thecool-down is completed, losses of period and energy can be eliminated.

Fourth Embodiment (see FIGS. 6 and 7)

When a period after an engine is stopped by an automatic stop controluntil restarting the engine is increased particularly in the cold time,the engine 1 is cooled down and its restart becomes troublesome and atthe same time a load on the engine or the like is increased.

Thus, in the fourth embodiment, the controller 2 is provided with anengine stop controller (corresponding to the engine controller 3 inFIG. 1) 7 for automatically stopping the engine 1 and an engine startcontroller 8 for automatically warming up the engine after the engine isautomatically stopped. In addition to a warm-up ensuring action beforethe engine is automatically stopped in the first embodiment, the warm-upoperation of the engine is automatically performed as required after theengine is automatically stopped.

An action of the fourth embodiment will be described with reference toFIG. 7. When the detected water temperature A reaches the warm-upcompletion temperature As or more after it is determined that theautomatic stop conditions are met in Step S31, the engine 1 isautomatically stopped (Steps S32 and S33).

When the detected water temperature A reaches a warm-up starttemperature As3 or less predetermined as a temperature at which thewarm-up operation should be started after the engine is automaticallystopped (YES in Step S34), the engine 1 is automatically started by acommand signal from the engine start controller 8 so that the warm-upoperation is started (Step S35).

After that the processing flow returns back to Step S31 and the warm-upoperation is performed in Step S33 through Step S32 until the engine 1is automatically stopped.

Other Embodiments

(1) A temperature of cooling water is detected as a temperature of aportion where a temperature is increased in accordance with theoperation of the engine in the above-mentioned respective embodiments.Alternatively, a working oil temperature or an exhaust temperature maybe detected.

(2) The fourth embodiment adopted a configuration in which the warm-upensuring action and the automatic warm-up action are combined with eachother. However, to enhance protection effects of the engine and thelike, the following combinations may be used:

-   -   (i) the cool-down action of the second or third embodiment and        the automatic warm-up action of the fourth embodiment;    -   (ii) the warm-up ensuring action and the cool-down action;    -   (iii) the warm-up ensuring action, the cool-down action and the        automatic warm-up action.

In this case, any two or all of the warm-up ensuring action for notautomatically stopping the engine before the completion of the warm-upoperation, the automatic cool-down action for performing the cool-downoperation as required before the engine is automatically stopped and theautomatic warm-up action for automatically maintaining a warm-up stateof the engine can be obtained as the combination.

That is the warm-up ensuring action and the cool-down action, thecool-down action and the automatic warm-up action, the warm-up ensuringaction and the automatic warm-up action, or all of the three actions canbe obtained.

Accordingly, the protection effects of the engine and the like are veryhigh.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, since anautomatic stop control always serves after a warm-up operation of anengine is completed, there is no fear that the engine is automaticallystopped keeping a low temperature state before warming up. As a matterof course, the engine is not restarted under a non warm-up state.Therefore, a load on the engine and peripheral devices can be reduced.

Further, there are no troubles of canceling the automatic stop controlbefore warming up and of restarting the engine for warming up.

1. An engine control device for a construction machine, characterized inthat said engine control device comprises an engine as a power source,control means for performing an automatic stop control to automaticallystop said engine when a predetermined automatic stop condition is met,and warm-up state detecting means for detecting a warm-up state of saidengine and wherein said control means is adapted to perform saidautomatic stop control in a condition that completion of a warm-upoperation for said engine is detected by said warm-up state detectingmeans.
 2. An engine control device for a construction machine,characterized in that said engine control device comprises an engine asa power source, control means for performing an automatic stop controlto automatically stop said engine when a predetermined automatic stopcondition is met, and cool-down necessity detecting means for detectingwhether or not said engine is in a state where a cool-down operation isrequired and wherein said control means is adapted to perform saidautomatic stop control in a condition that a cool-down period is keptbefore said engine is automatically stopped when said cool-downnecessity detecting means detects that said engine is in an operationstate where said engine requires the cool-down operation.
 3. The enginecontrol device for the construction machine according to claim 2,wherein, as said cool-down necessity detecting means, a temperaturedetector for detecting a temperature of a portion whose temperatureincreases in accordance with an operation of said engine, and saidcontrol means is adapted to select a required cool-down period inaccordance with the detected temperature by said temperature detector.4. The engine control device for the construction machine according toclaim 3, wherein said control means automatically selects one of aplurality of cool-down period patterns in accordance with the detectedtemperature by said temperature detector.
 5. The engine control devicefor the construction machine according to claim 2, wherein said controlmeans stops said engine when completion of the cool-down operation ofsaid engine is detected by said cool-down necessity detecting means. 6.An engine control device for a construction machine, characterized inthat said engine control device comprises an engine as a power source,control means for performing an automatic stop control to automaticallystop said engine when a predetermined automatic stop condition is met,and warm-up necessity detecting means for detecting whether or not saidengine is in a state where a warm-up operation of said engine isrequired, and wherein said control means is adapted to automaticallyrestart said engine when said warm-up necessity detecting means detectsthat said engine is in the state where the warm-up operation is requiredafter said engine is automatically stopped by said automatic stopcontrol.
 7. The engine control device for the construction machineaccording to claim 6, wherein said engine control device furthercomprises warm-up state detecting means for detecting a warm-up state ofsaid engine and said control means performs said automatic stop controlin a condition that completion of the warm-up operation is detected bysaid warm-up state detecting means.
 8. The engine control device for theconstruction machine according to claim 2, wherein said engine controldevice further comprises warm-up state detecting means for detecting awarm-up state of said engine, and said control means is adapted toperform said automatic stop control in a condition that completion of awarm-up operation is detected by said warm-up state detecting means. 9.The engine control device for the construction machine according toclaim 2, wherein said engine control device further comprises warm-upnecessity detecting means for detecting whether or not said engine is ina state where a warm-up operation is required, and said control means isadapted to automatically restart said engine when said warm-up necessitydetecting means detects that said engine is in the state where thewarm-up operation is required after said engine is automatically stoppedby said automatic stop control.
 10. The engine control device for theconstruction machine according to claim 2, wherein said engine controldevice further comprises warm-up state detecting means for detecting awarm-up state of said engine and warm-up necessity detecting means fordetecting whether or not said engine is in a state where a warm-upoperation is required, and that said control means comprising: A)performing an automatic stop control in the condition that completion ofthe warm-up operation is detected by said warm-up state detecting means;and B) restarting said engine when said warm-up necessity detectingmeans detects that said engine is in the state where the warm-upoperation is required after said engine is automatically stopped by saidautomatic stop control.
 11. The engine control device for theconstruction machine according to claim 3, wherein said engine controldevice further comprises warm-up state detecting means for detecting awarm-up state of said engine, and said control means is adapted toperform said automatic stop control in a condition that completion of awarm-up operation is detected by said warm-up state detecting means. 12.The engine control device for the construction machine according toclaim 4, wherein said engine control device further comprises warm-upstate detecting means for detecting a warm-up state of said engine, andsaid control means is adapted to perform said automatic stop control ina condition that completion of a warm-up operation is detected by saidwarm-up state detecting means.
 13. The engine control device for theconstruction machine according to claim 5, wherein said engine controldevice further comprises warm-up state detecting means for detecting awarm-up state of said engine, and said control means is adapted toperform said automatic stop control in a condition that completion of awarm-up operation is detected by said warm-up state detecting means. 14.The engine control device for the construction machine according toclaim 3, wherein said engine control device further comprises warm-upnecessity detecting means for detecting whether or not said engine is ina state where a warm-up operation is required, and said control means isadapted to automatically restart said engine when said warm-up necessitydetecting means detects that said engine is in the state where thewarm-up operation is required after said engine is automatically stoppedby said automatic stop control.
 15. The engine control device for theconstruction machine according to claim 4, wherein said engine controldevice further comprises warm-up necessity detecting means for detectingwhether or not said engine is in a state where a warm-up operation isrequired, and said control means is adapted to automatically restartsaid engine when said warm-up necessity detecting means detects thatsaid engine is in the state where the warm-up operation is requiredafter said engine is automatically stopped by said automatic stopcontrol.
 16. The engine control device for the construction machineaccording to claim 5, wherein said engine control device furthercomprises warm-up necessity detecting means for detecting whether or notsaid engine is in a state where a warm-up operation is required, andsaid control means is adapted to automatically restart said engine whensaid warm-up necessity detecting means detects that said engine is inthe state where the warm-up operation is required after said engine isautomatically stopped by said automatic stop control.
 17. The enginecontrol device for the construction machine according to claim 3,wherein said engine control device further comprises warm-up statedetecting means for detecting a warm-up state of said engine and warm-upnecessity detecting means for detecting whether or not said engine is ina state where a warm-up operation is required, and that said controlmeans comprising: A) performing an automatic stop control in thecondition that completion of the warm-up operation is detected by saidwarm-up state detecting means; and B) restarting said engine when saidwarm-up necessity detecting means detects that said engine is in thestate where the warm-up operation is required after said engine isautomatically stopped by said automatic stop control.
 18. The enginecontrol device for the construction machine according to claim 4,wherein said engine control device further comprises warm-up statedetecting means for detecting a warm-up state of said engine and warm-upnecessity detecting means for detecting whether or not said engine is ina state where a warm-up operation is required, and that said controlmeans comprising: A) performing an automatic stop control in thecondition that completion of the warm-up operation is detected by saidwarm-up state detecting means; and B) restarting said engine when saidwarm-up necessity detecting means detects that said engine is in thestate where the warm-up operation is required after said engine isautomatically stopped by said automatic stop control.
 19. The enginecontrol device for the construction machine according to claim 5,wherein said engine control device further comprises warm-up statedetecting means for detecting a warm-up state of said engine and warm-upnecessity detecting means for detecting whether or not said engine is ina state where a warm-up operation is required, and that said controlmeans comprising: A) performing an automatic stop control in thecondition that completion of the warm-up operation is detected by saidwarm-up state detecting means; and B) restarting said engine when saidwarm-up necessity detecting means detects that said engine is in thestate where the warm-up operation is required after said engine isautomatically stopped by said automatic stop control.